Load compensating brake equipment



Nov. 20, 1951 s, coo ETAL LOAD COMPENSATING BRAKE EQUIPMENT 2 SHEETS -SHEET 1 Filed Jan. 25, 1950 INVENfiORS Earle 8. 000K Glenn TMoClur'e John W Ru h Q am ATTORNEY Nov. 20, 1951 E. s. COOK ETAL LOAD COMPENSATING BRAKE EQUIPMENT 2 SHEETS-SHEET 2 Filed Jan. v25, 1950 mm RV m2 QN QNmON INVENTORS Earle 5'. U0 0K Glenn IMcOlure BY John WRU Sh A T TORNE Y Patented Nov. 20, 1951 2,575,943 LOAD COMPENsA'rJNG BRAKE EQUIPMENT Earle S. Cook, Forest Hills, Glenn T. McClure, McKeesport, and John W. Bush, Wilkinsburg, Pa., assignors to Westinghouse Air Brake Company, a corporation of Pennsylvania Application January 25, 1950, Serial No. 149,426

20 Claims.

This invention relates to variable load brake equipment and more particularly to the type adapted to be automatically adjusted to vary the degree of braking of a vehicle in accordance with the loaded condition thereof.

The present trend toward the use of light weight materials in the construction of railway freight cars has resulted in much higher ratios of gross to tare weight than ever before encountered. A brake design to provide desired deceleration and stopping of an empty car of this type is therefore wholly inadequate for the car when loaded, and conversely, a brake designed to provide desired deceleration and stopping of the loaded car could not be tolerated on the empty car since it might result in execessive and damaging train shock and cause undesired sliding of the car wheels.

The principal object of the invention is therefore the provision of an improved variable load brake equipment adapted to automatically vary the degree of braking of a car in accordance with the load condition thereof.

According to this object we employ a single brake cylinder device for braking the car, the piston therein having the usual pressure chamber at the front side thereof and a second pressure chamber at the opposite side. The well-known AB valve is used '-for varying the pressure of fluid in the usual pressure chamber at the front of the brake cylinder piston, and a novel relay valve device embodying a scale beam having a fulcrum automatically adjustable according to the empty or loaded condition of the car, is arranged to-operate upon supplyof fluid under pressure to the usual pressure chamber to vary pressure of fiuid in the second chamber, from atmospheric pressure for a fully loaded car, inversely in proportion to the degree of .the .load, for thereby varying the effect of the pressure of .fluid on the front of the piston to apply the brakes,.as ,a result of which, the degree of braking of the car willbe varied in proportion to the degreeof the load carried thereby. In other words, when the car is, fully loaded, the pressure in the second chamber will be atmospheric pressure so that the degree of the brake application of the car will be governed solely by the pressure of fluid in the pressure chamber in the front of the brake cylinder piston in the usual manner. When the car is less than fully loaded the degree of braking will be governed by the differential in pressure acting on opposite sides of the brake cylinder piston, and

this difierential will be of minimum degree when the car is empty and will be increased in pro- Cal portion to the degree of load on the car disappears on the fully loaded car.

Another object is to provide novel means in a brake equipment of the above described type for relieving the scale beam above mentioned, of force pressing it against its fulcrum prior to adjusting of said fulcrum relative to said scale beam.

Other objects and advantages will become apparent from the following more detailed description of the invention.

In the accompanying drawings, Fig. 1 is a diagrammatic view, partly in outline and partly in section, of a variable load brake equipment embodying the invention; Fig. 2 is a sectional view taken on the line 2-2 in Fig. 1; and Fig. 3 is a diagrammatic View of a modification of a part of the equipment shown in Fig. 1.

Descriptionmg. 1

As shown in Fig. l of the drawings, the variable load brake equipment comprises a brake controlling valve device I to which is connected the usual brake pipe 2, auxiliary reservoir 3, emergency reservoir 4 and a brake cylinder pressure retaining valve device 5, as well as a brake cylinder device 6. The equipment further comprises ,a load reservoir l, a load compensating or-variable leverage relay valve device 8 and a weighing gear or adjusting mechanism :9 associated with said compensating device. The auxiliary, emergency and load reservoirs are preferably pro.- vided in a common casing separated by dividing walls as shown in the drawing. All the above enumerated structure is adaptedto be carriedby a sprung part of the car such as by the bottom .of :the floor thereof.

The brake controlling valve device l may .beof substantially the same construction and have the same operating characteristics as the valve device fully described in the patentflissued .to Clyde C. Farmer, No. 2,031,213 on FebruaryI-B, 1936,1nyiewof which it is 2notdeemed necessary to show and describe this device indetail. Brief,- v1y, however, the brake controlling valve device ,1 comprises a service portion H adapted to opup a er i and emer en r ed ct qn i pressure of fluid in the brakepipe 2 for supplying flui u d press e o au lia y ese oir; to abrake cylinder pipe II and thence to brake cylinder device 6 for, upon a service reduction ,inbrake pipe pressure, effecting a service applioationpf brakes on thecar. The brake controlling valvedevice I also comprises an emergency portion l2 whichis adapted to operateonly upon an emergency reduction in pressure of fluid brake pipe 2 for supplying fluid under pressure until it The brake cylinder device 3 comprises a. hollow cup-shaped casing I4 to the open'end of which is secured an annular pressure head l5 from which projects a hollow cup-shaped non-pres? sure head It. A brake cylinder piston H is slidably mounted in the casing Ht'and'at one side thereof is the usual or main pressure charmber l8 to which is connected the pipe The brake cylinder piston ll comprises a piston head l3 to one face of which is connected a flexible packing cup for preventing leakage of fluid time pressure from the pressure chamber l8 to theopposite side of the piston. Secured to and projecting from the piston H in a direction away from pressure chamber l3 is a hollow stem 2| .the opposite end of which is slidably mounted in .a ring '22 secured in the pressure head I5. Carried by the pressure head l5 and ring 22 is a packing cup or ring 23 having sealing or sliding contact with the outer peripheral surface of the stem 2| for preventing leakage of fluid under pressure from a compensating, or balancing, pressure chamber 24 formed around said'stem between the pressure head l5 and the piston toa non-pressure chamber 25 formed within said stem and open to the interior of the non-pressure head I6 and thence to atmosphere through aport 26 in said non-pressure head. The chamher; 24 is open to a pipe 21 through which fluid under pressure is adapted to be supplied to and released from said chamber by operation of the compensating valve device 8, in a manner which will be hereinafter described.

The piston I9 is provided with a hollow boss '28 projecting into the hollow stem 2| in coaxial relation to said head and stem, and one end of .a hollow rod 29 is secured in said boss. The rod 23 extends through the non-pressure chamber -25 and a bore provided in the outer ,end of the non-pressure head l3 to the exterior thereof, .said rod being hollow to accommodate the usual push rod (not shown) for connecting the piston head" with the brake rigging (notshown) of the car, in the conventional manner. Encircling .the hollow rod is av brake cylinder piston release spring 30, one end of which bears against the piston head IQ for moving the brake cylinder piston I! to its brake release position, in which it is shown in the drawing. The opposite end of the release spring is supported on the non-pressure head l6. V

The load compensating valve device 8 comprises pilot and balancing flexible diaphragms f6 mu'nication with passage 39.

gaging the opposite face of diaphragm 3| is a follower 40 provided on one end of a stem 40a, the opposite end of which engages an equalizing member or beam 4| near one end within a pocket 32. Engaging the opposite end of the beam 4| within a similar pocket 43 is one end of a stem 44.. The opposite end of stem 44 is in a form of a follower 45 which is secured to the side of the diaphragm 32 opposite chamber 36 by means of a nut 45 contained in said chamber.

' The nut 46 has an extension 48 slidably mounted in a bore in the casing and separating chamber 35 from a chamber 49 which is in com- The nut 45 and extension 48 thereof are provided with an axial bore containing a coil spring 5| and open at one end to a chamber 52 in the casing and provided around the opposite end with a valve seat arranged for engagement by a release valve 53. The valve 53 is contained in chamber 49 and has .a fluted stem 54 slidably mounted in bore 50 and operatively engaging the spring".5|. Chamber 52 is in constant communicationwith atmosphere through a passage 55. It will be noted that the diaphragm stems 4|]; 44' and beam4| are containedin chamber 52 'and that the lower faces of the two diaphragms 3|, 32 are both subject to atmospheric pressure in "said chamber. a

The release valve 53, opposite the fluted stem 54, has an enlarged annular collar 56, one side of which is provided for contact'with a combined valve guide and stop element 51'projectingfrom the casing in the chamber 49,"while the opposite side is arranged for engagementby the endof a'fluted stem 58 of'a coaxially arranged .fluid pressure supply valve 59 which is contained in a chamber 55. The chamber 50 is open to a passage 6| leading to a pipe 62' which is connected to the load reservoir 3. A bias spring 63 contained in chamber bears on the supply valve 53 for urging it toward its seat.

The side of the equalizing member or beam 4| opposite that from which the diaphragm follower stems 40 and 44 project is supported-on a fulcrum, preferably in the shape of aninverted V-shaped knife edge 64 which is associated with a piston rod 14. a V I a The equalizing member or beam 4l is held against longitudinal movement by a yoke-"Ill (Fig. 2) pivoted on one end on a pin f|| carried in arms 12 projecting from the casing. The arms of the yoke 10 are disposed at opposite sides of the beam 1| and their ends are pivotally connected to said beam near its center by a pin 73. The fulcrum 64 is adapted to be adjusted relative to the beam 4| longitudinally thereof by the piston rod 14 to provide at its line of contact 'with thebeam a fulcrum therefor, the yoke' 10 being effective during such'adjustment and at all other times, to prevent longitudinal movement of said beam but to in no way interfere with rocking movement of the beam about its connection with the fulcrum 64, which will be laterdescribed. 7 l

' Connected to one end of the piston rod 14 is a bias piston 17 open at one side to 'a control or pressure chamber 18, while the opposite side of said piston is open to atmospheric chamber 52. A shoulder 79 in the casing is arranged for contact by piston Ti for limiting movement thereof in the direction of the left hand, movement in the direction ,of the right hand being limited by contact with the casing. The pistonrrod 14 projects mm th Pi n l t ,th mbe j and a bore in a wall 89 which separates .said chamber from a chamber M in the casing, the end of said rod opposite saidpiston being supported by contact with the wall of said bore.

The fulcrum 64 has two extreme positions with respect to the equalizing member or beam 41, one position being defined by contact between piston I1 and shoulder I9, which position will hereinafter be referred to as the empty position, which said fulcrum will occupy when the car is empty. In the other extreme position to be hereinafter referred to as the full-load position, the fulcrum 64 will be substantially below the end of the diaphragm follower stem 49a and the piston 'ITI will be slightly spaced away from contact with the end wall of chamber 78, and this position will be assumed when the car is fully loaded. For various degrees of car load between empty and full-load the fulcrum 64 will assume a corresponding position between the empty and fullload positions, just mentioned. The automatic adjustment of fulcrum 64 to its different positions will be hereinafter described.

The piston rod I4 is provided with a plurality of teeth 83 along the side toward the beam 4| for engagement by teeth on one end of a latch or looking plunger 84 which is mounted to slide in the casing in a direction at right angles to the length of said rod. The end of the plunger 84 opposite the teeth 83 is in the form of a follower 85 secured by screw-thread means 86 to a latch or plunger control diaphragm 81 which is clamped around its periphery in the casing. At the side of the diaphragm 81 adjacent the follower 85 is a pressure chamber 88 to which fluid under pressure is adapted to be supplied for deflecting said diaphragm in a direction for moving the plunger out of locking engagement with piston rod 74. At the other side is a chamber 89 which is in constant communication with atmosphere I through a passage 90. A spring 9I operatively engages a wall in the casing and the screwthread means 85 for urging the plunger 84 to a position in which it is shown in the drawing, in which position said plunger is in looking engagement with the piston rod I4.

A check valve 93 contained in a chamber 94 is provided for closing'communication between said chamber and a chamber 95 into which extends a plunger 96 slidably mounted in a bore in the casing in coaxial relation to the diaphragm 9'! and abutting screw-thread means 86 so as to be actuated through the medium of said means by the diaphragm 81. With plunger 84 in looking engagement with piston rod I4 theend of plung- -er 96 is spaced from the check valve 93 a distance slightly exceeding the extent of movement of plunger 81 required to release it from said rod. Upon further movement, the plunger 95 is adapt- -ed to engage and unseat valve 93. A spring 9! contained in chamber 94 acts on check valve 93 for urging it to its seat. The ring seal 98 on plunger 96 prevents leakage'of fluid under pressure between chambers 94 and 95.

Spaced from and extending generally parallel to the bias piston 71 and its red" is an adjusting piston 99 and a rod I projecting from one side of said adjusting piston through a non-pressure chamber IIlI which is open to atmospheric chamber 52. At the opposite side of piston 99 is a pressure chamber I02 open to the bias piston pressure chamber I8 by way of passage I03, which passage also connects to chamber 95. Aspring I04 contained in the non-pressure chamber IOI and encircling the rod 100 is supported at one end on the casing, while its opposite end bears against piston 99 for urging said piston and rod to a position in which they are shown in the drawing. The end of rod I00 opposite to the piston end extends through an opening in a wall 105 separating chamber 52 from a chamber I06.

A lever I91 extending through an opening I08 in a horizontal portion of the casing wall is fulcrumed therein on a pin I59. The end of this lever in chamber BI is arranged for contact with the end of the piston rod I4 while the opposite end of said lever is disposed in a slot III) provided in the adjusting piston rod I90. The slot H9 is of such length as to permit the lever I9! to be free on pin I99 with the adjusting piston 99 in the normal position in which it is shown in the drawing, and to permit a chosen extent of movement of said piston against spring 94 before and when wall I I I of said slot engages the lever.

In chamber I96 the end of the adjusting piston rod I99 is operatively connected by means of a pin IE2 to one end of an arm II3 of a bell crank-like lever H4 which at its knee is ful crumed on a pin H5 secured in the casing. The lever has another arm IIS on the end of which there is provided a fixed cam surface II! arranged for contact by a roller I It provided in one end of a lever H9, the opposite end of which is secured to turn with a shaft I29 journaled in the casing. The cam surface II! is of least radius at the end adjacent the roller H8, as viewed in the drawing. Pivoted by pin I2! to the bell crank arm ii adjacent the opposite end of the cam surface Ill, is an adjustable cam element I22 having a cam surface I23 constituting an extension of the fixed cam surface I39. The cam element IE2 is urged to rotate in a counter-clockwise direction about the pin I2l as viewed in the drawing by a spring I24 acting through the medium of a plunger I25 which engages the upper end of said element, this rotation however being limited by an adjusting screw I23 mounted in the lower end of lever arm I I6. A look. nut M1 is provided for contact with the lever arm I I5 for securing the screw in an adjusted posit-ion.

A lever I28 disposed outside of the casing has one end secured to turn with the shaft I29 while connected to its opposite end by a pin IE9 is one end of a connecting rod I39. The other end of the rod I39 is connected by a pin I3! to one arm I32 of a bell-crank lever I33 fulcrumed at its knee on a pin I34 carried by a sprung part I35 of the car. The other arm I 39 of the bell-crank lever I33 is connected by a pin I3! to the upper end of a rod I39 which has formed integrally therewith at itslower end a $-shaped measuring portion I39 provided with a striking surface 54'? for contacting the underside of an unsprung part I4I disposed within said portion in a substan tially horizontal position of said surface. The part I4I may be in the form of a rod extending transversely of the car truck or may constitute an axle of a truck wheel and axle assemblage. Interposed between the sprung part I35 and a spring seat I42 mounted on red I39 is a spring I43 which encircles said rod and constantly urges the rod in a downward direction toward the position in which it is shown in the drawing.

The brake cylinder cut-off valve device 35 comprises a diaphragm I44 clamped at its periphery between two sections of the casing and having at one side a control chamber I45 to which fluid under pressure is adapted to besupplied from a brake pipe cut-off valve'portion I49 by way of a branch of a-passage ..I4'I. .Atathe,

:.other side ofathe dia hragm I441'is a chamber 148 which is in constant communication. with. atmosphere through passage .I49.... Contained the chamber I48 is a follower..l58 having an axial bore II which is constantly opento, chamber I48 by way of ports I52. A spring I53 operatively engages a wall in the casing and said follower for urging said follower toward the position in which it isrshown in the drawing. Contained in the bore I5I is an exhaust valve I54 arranged tosealingly engage a valve seat I55 encircling said bore, and also a bias spring I55 which urges the exhaustv valve I54 towards its seated position in which it is shown. The valve I54 is provided with a-fluted stem 154a by which it is supported in the bore 'I5 I and which extendsintoa chamber I51 which is connected to the'chamber 33 .through the passage 34. Contained in the chamber.I5 1 is a supply valve I58 having'a fluted stem spring I32 for urging valve I59 toward its unseated position in which it is shown in the drawmg.

The compensating cylinder cut-01f valve device 31 comprises a diaphragm I64 clamped around its periphery between two sections of the casing and having at one side a control chamber I65 in open communication with control chamber I45 through a passage I65a. At the other side of diaphragm I54 is a chamber I66 which is open to atmosphere by way of a vent passage I61. Contained in chamber I66 is a follower I68 which abuts the diaphragm I64 and has an axial bore I69 in communication with said chamber through ports I19. Interposed between and operatively engaging a wall of a casing and the follower I68 is a spring ill for urging the follower and diaphragm I64 toward the position in which it is shown in the drawing. Contained in the bore I69 is a valve I12 arranged to engage a valve seat I13 which encircles said bore. A bias spring I1Ia is provided in the bore I69 for urging the valve I12 to its seated position in which it is shown in the drawing. The valve I12 is provided with a fluted stem I14 which extends through bore I69 into a chamber I15 which is open to passage 39 leading to chamber 49. Contained in chamber I15 is a valve I16 having a fluted stem 11 slidably mounted in a suitable bore in the casing and extending into a chamber I18 which is connected to a passage I19 and pipe 21 leading to chamber 24 in the brake cylinder device 6. Interposed between a wall in the casing and the free end of fluted stem I11 is a spring I89 for urging valve I16 out of engagement with valve seat I13 and into abutting engagement with the end of fluted stem I14.

The brake pipe cut-oil valve device I46 comprises two coaxially arranged flexible diaphragms I82 and I83 clamped around their edges between two sections of the casing in spaced apart relation to each other. Between the two diaphragms is a chamber I85 which is open to atmosphere through a vent port I86 and which contains a spring I81, the opposite ends of which bear against followers I88 and I69 engaging diaphragms I82 and I83, respectively, for urging said diaphragms apart. At the outer face of diaphragm I82, which is of larger area than diaphragm I83, is a pressure chamber I96 whichis connected to the passage I41, which passage is also connected to latch chamber 88. At the op- 'posite face of 'diaphragmfI83 is' a'valve chamber I92 which is in constanticom'munication with. the brake pipe 2 through. a. passage I93, a choke I94, a passage I95. and thence by way of. a pipe I96 in which there is provided. a choke I91. In actual practice the pipe I96 is connected directly to pipe bracket I3 of the AB valve device I and through said pipe bracket to the well-known brake pipe connection (not shown) therein,and the choke I91. is disposed in said bracket, but for the purpose of simplicity in the present application, the pipe I96 is shown in the drawing connected directly to the brake pipe 2, as above described. l

The cut-off valve device I46 further comprises a slide valve I98 contained in chamber I92 and mounted therein between spaced shoulders I99 formed on a stem 288. One end of the stem-200 is connected by follower I89 and a screw-thread means 28I to the center of diaphragm-l83 for rendering the slide valve I98 movable by and with said diaphragm, V

Connected to the seat of the cut-oil slide valve I98 is a passage 282 which leads 'to atmosphere, a passage I63 which leads to chamber 95 and to the biasing and adjusting piston chambers 18 and I62, and a passage 264 which leads to check valve chamber 94 and to a timing reservoir 205.

The load compensating device 8 further cornprises two check valves 286 and 201 arranged in series in a connection between passage I93 and a branch of passage 2I3 and a bias spring 208 acting on check valve 266 for urging it to its seat. l p

Operatz'01tFig. 1

.Let it be initially assumed that the brake equipment is devoid of fluid under pressure and that to condition the equipment for operation, fluid under pressure is supplied to the'b rake pipe 2 in the usual manner.

' left-hand positions in which said diaphragm abuts off valve device 31 devoid of fluid under pressure spring I1I will act on the follower I68 to hold said follower and diaphragm I64 in their extreme left-hand positions in which said diaphragm abuts a portion of the casing. In this position spring I1Ia is permitted to hold exhaust valve I 12 in its seated position and spring I8!) is permitted to hold supply valve I16 unseated thereby con necting chambers I15 and I18.

' The brake controlling valve device I will respend in the usual manner to the pressure of the load compensating valve device 8wil1 also be open to atmospher e by' 'way of I passage 34, chamber I51 in the brake cylinder cut-ofi'valve device 35., chamber 160, passag IBI an pip II, which. will permit spring 209 to deflect pilot diaphragm 3I into a position of contact with a portion of the casing, in which these parts are shown in the drawing.

With the pilot diaphragm 3| positioned as just described, any substantial amount of fluid under pressure will act on balancing diaphragm 33 to deflect it downward, the spring 69 will seat the fluid pressure supply valve 59 and the collar 56 on the release valve 53 will be just out of contact with the supply valve stem 59 and in engagement with the stop element 51 which will hold said release valve out of contact with its seat on a nut extension 48. With the release valve 53 thus open chambers 49 and 36, and thereby the compensating pressure chamber 24 in the brake cylinder device 6 connected to chamber 49 by way of pipe 21, passage I19, chambers I89 and I15, and passage 39 will be open to atmosphere by way of chamber 52 and port 55. With both pressure chambers I8 and 24 in the brake cylinder device 6 thus open to atmosphere the brake cylinder piston I1 will assume its brake release position, in which it is shown in the drawing, under the action of the release spring 39.

When fluid under pressure is supplied to the brake pipe 2 for charging the equipment as above mentioned, fluid will also flow therefrom through choke I91 and pipe I96 to passage I95 in the load compensating valve device 8 and thence past the check valves 291 and 296, through a passage 2H), and pipe 62 to the load reservoir 1 for charging said reservoir with fluid at the pressure carried in the brake pipe At the same time fluid supplied from the brake pipe to the load compensating relay valve device 9 will flow from passage I95 through choke I94, passage I93 and passage I19 into valve chamber I92 of the cut-off valve device I46.

The parts of the cut-off valve device I46 will occupy the cut-in position in which they are shown in the drawing until the pressure of fluid in the brake pipe 2 acting in valve chamber I92 is increased to a chosen degree, such as ii) pounds, and during the time required to obtain this pressure, fluid from valve chamber I92 will flow through a port 2II in the slide valve I98 to passage 294 whence it will flow to check valve chamber 94 and to the timing reservoir 295, and at the same time fluid under pressure will also flow from chamber I92 through a port 2I2 in the slide valve I98 to passage I41 and thence to latch diaphragm chamber 88 and also to chamber I45 in the brake cylinder cut-off valve device 35, whence it will flow through passage IBM to chamber I65 in the compensating cylinder cut-off valve de vice 31.

When pressure of fluid supplied to chamber I65 in the load compensating cylinder cut-oil valve device 31 is increased to a degree, such as 8 pounds, sufficient to overcome the opposing force of spring I1I, the diaphragm I64 will deflect inwardly. It will be understood that the strength of spring I1Ia is of a higher value than that of spring I80. Consequently, the initial inward deflection of diaphragm I6 3 will cause supply valve I16 to be moved to its seated position first, in which communication between chambers I and I18, and therefore between load compensating chamber 24 in the brake cylinder device 6 and chamber 49, is cut off.

Upon an increase in the pressure of fluid supplied to chamber I65 to a predetermined higher degree, such as 10 pounds, suflicient to overcome the additional opposing force of spring I1'I a, diaphragm I64 will be deflected further inward, causing the valve seat I13 to move away from the exhaust valve I12. With valve I12 unseated any fluid under pressure which might be present in chamber 49 will flow through passage. 39, chamber I15, past valve I12, into chamber I69 and thence through ports I19 in follower I68 to chamber I66 which is open to atmosphere by way of passage I61. In this manner any force which might be exerted on the left-hand end of the beam M, as viewed in Fig. l of the drawings, by reason of fluid under pressure in chamber 49 is dissipated.

When the pressure of fluid supplied to chamber I45 in the brake cylinder cut-off valve device 35 is increased to a degree, such as 10 pounds, sufficient to overcome the opposing force of spring I53, the diaphragm Hid will deflect inwardly. It will be understood that the strength of spring I56 is of a higher value than that of spring I62. Consequently, the initial inward deflection of diaphragm I44 will cause supply valve I58 to be moved to its seated position first in which communication between chambers I69 and I51, and therefore between pressure chamber 29 in the brake cylinder device 6 and chamber 33 in the relay valve device 8, is cut off.

Upon an increase in the pressure of fluid supplied to chamber I45 to a predetermined higher degree, such as 12 pounds, suflicient to overcome the additional opposing force of spring I56, diaphragm I44 will be deflected further inward, causing the valve seat I59 to move away from the exhaust valve I54. With valve I54 unseated any fluid under pressure which may be present in pilot chamber 39 will flow through passage 34, chamber I51, chamber I9I and ports I52 in the follower I59 to chamber I48 and thence by Way of vent passage I49 to atmosphere. In this manner any force which might be exerted on the right-hand end of the beam M, as viewed in-Fig. 1 of the drawings, by reason of fluid pressure in chamber 93 is dissipated.

When the pressure of fluid supplied to the latch diaphragm chamber 99 is increased to a degree, such as 15 pounds, sufficient to overcome the opposing force of spring 69, the diaphragm 81 will deflect against said spring to actuate the plunger 96 into contact with the bottom surface of the check valve 93. This distance of deflection will be suflicient to draw the latch 84 out of locking engagement with the teeth 83 on the piston stem 14, following which the plunger 96 will unseat the check valve 96 against the additional opposing force of the spring 91. Fluid under pressure supplied from the cut-off valve chamber I92 to the check valve chamber 94 will then flow to chamber 95 and thence through passage I93 to the adjusting piston chamber I 92 and to bias piston chamber 19. Fluid under pressure thus provided on the bias piston 11 will promptly move said piston to the position in which it is shown in the drawing, if it is not already in said position, for thereby actuating the fulcrum 64 to its empty position, in which it is also shown in the drawing.

When the pressure of fluid in chamber I02 acting on the adjusting piston 99 is increased to a degree sumcient to overcome the opposing force of spring 894, said piston will move against said spring and thereby rock the bell cranlg like lever H4 in a clockwise direction about pin H5 and, through the medium of the cam surface II1, the levers I I 9 and I28 will be rocked in a counterclockwise direction and pull the connecting rod I30 in the direction of the right hand. This 'm'ovementof the connecting rod I30 causes the bell crank lever I33 to rock about the pin I34 vwhich will in turn draw the surface I 90 of the 'measuring element I39 into contact with the unsprung part I4I of the car truck, which will prevent further movement of the piston 99 by pressure of fluid in chamber I02. 1

When the equipment is devoid of fluid under pressure, as well as after an adjusting operation .such as being described, the measuring element I39 will occupy the position with respect to the unsprung part I 9| of the car truck in which it is shown in the drawing when the car is empty, so that during adjustment movement piston 99 will be stopped by contact between said element and the unsprung part MI when the surface -III on the adjusting piston rod I just contacts the adjacent end of lever I01 with the other end of said lever just in contact with the ad- .jacent end of the bias piston rod 14 and with the bias piston 11 and fulcrum 94 in empty position above described and shown in the drawing. Furthermore, with the car empty, the roller H8 carried on the end of lever H9 will move just to the junction of the fixed cam surface II1 on the bell crank lever II and the adjustable cam surface I23 on the adjustable element I22 when the measuring element I39 contacts the unsprung truck part I4I.

i If thecar is fully loaded, the body thereof will occupy a position closer to the unsprung part I II of the truck than when the car is empty.

In this fully loaded position the lower portion of the measuring element I39 may therefore initially occupy a position such as indicated by a dot and dash line 2 I4 in the drawing and therefore require a greater movement before it comes into contact with the unsprung part MI to thus "permit a greater movement of the adjusting piston 99 by pressure of fluid in chamber I02 than when the car is empty. The adjustable .cam I22 will therefore become effective to operate levers H9 and I33 during this greater movement and said cam will be so adjusted by regulating screw I 26 as to permit suflicient movement of ,piston 99 to actuate lever I01 to move the bias 'piston rod 14 and piston 11 against pressure of Yfluid in chamber 18 to a position in which piston '11 is in substantial contact with the right-hand 'end'wall-of chamber 18 and in which the ful-' crum 60 will therefore occupy its full-loaded position substantially under the end of the diaphragm follower stem 40.

' For various degrees of load on a car between assume corresponding positions between the empty and full load positions thereof, as will be clear from the above description.

The cam I23 is ad ustable in accordance with the amount of deflection of the car body supporting springs (not shown) between the empty and fully loaded conditions thereof in order to obtain the desired positioning of fulcrum 64 for the empty and fully loaded conditions of the car, regardless of variations in the deflection and characteristics of said spring such as encountered on different cars, as fully described in Patent No. 2,482.246, issued to Cook et al. on

September 20, 1949.

While the fulcrum 64 of the load compensating valve device 9 is being adjusted to a position corresponding to the empty or load condition 0f the car asjust described, the pressure of fluid in diaphragm chamber I of the cut-off valve portion I46 continues to increase with the increase in the diaphragm chamber I92 and brake pipe 2. This increase in pressure in chamber I90 acts to gradually deflect diaphragm I82 toward the righthand to correspondingly increase the pressure of spring I81 against that of diaphragm I83 so as to offset the increase of pressure of fluid in chamber I92 acting on diaphragm I83 and to thus hold the latter diaphragm and slide valve I98 in their cut-in position in which they are shown in the drawing. Eventually the pressure of fluid in diaphragm chamber I90 will become increased to a degree at which deflection of diaphragm I82 will be stopped by contact of the diaphragm follower I88 with the casing, thereby limiting to a certain selected degree the increase in pressure of spring I81 against diaphragm I83. Then when the pressure of fluid in the brake pipe 2 and in valve'chamber I 92 becomes increased to a certain higher degree, such as 40 pounds, which is sumcient to overcome the opposing increased pressure of the spring I81, the diaphragm'I93 will be deflected toward the left hand to a position defined by contact between the diaphragm follower I89 and the-casing for thereby shifting theslid valve I98 to its cut-out position.

In the cut-out position of the slide valve I98 the port 2I5 therein connects passage I 41 to the atmospheric passage 202 whereupon fluid under pressure is vented from the diaphragm chamber 88 and from chambers I45 and I65 in'thebrake cylinder cut-off valve 35 and the compensating cylinder cut-ofl valve 31, respectively, and diaphragm chamber I90 to atmosphere. The venting of fluid under pressure from the latter chamber permits the diaphragm I82 to be returned to the position defined by contact with the lefthand end wall of chamber I90 by spring I81, which reduces the force of said spring on the diaphragm ,I 83 to a degree which will prevent return of the latter diaphragm and of the slide valve I98 to their cut-in position until the brake pipe pressure effective in valve chamber I92 is subsequently reduced to a degree less than a rela- .tively low degree, thereby insuring that the cuttrain.

The venting of fluid under pressure from the diaphragm chamber 88 upon movement of the cut-out valve I98 to its cut-out position permits spring 9I to return diaphragm 81to the position in which it is shown in the drawing. This operation actuates plunger 95 out of engagement with check valve 93 and into locking engagement with the bias piston rod- 14. The check valve 93 will then be seated by the spring 91.

At the same time as fluid under pressure is being released from passage M1 by way of port 2I5, passage 2I6 in slide valve I98 connects passages I03 and 204 to the atmospheric passage 202 by way of the choke connection H1. The timing reservoir 285 previously charged with fluid. under pressure from the brake pipe, is thus placed in communication with the adjusting piston; chamber I02 and bias piston chamber 18, and

said reservoir and these chambers are all open to atmosphere through the restricted connectionv 2I1, whereby the pressure of fluid in saidreservoir and chambers'will be gradually reduced at a rate determined. by the. flow capacity of said.

connection relative to the volume of said reservoir and chambers.

The volume of the timing reservoir 295 with respect to the flow capacity of the choke connection 2I1 and the combined volume of chambers 18 and H12 is such as to maintain sufficient pres sure in chamber F8 on the bias piston 11 and in chamber I92 on the bias piston 99 to firmly hold the bias piston rod 14 against lever I91 and the measuring element I39 in contact with the unsprung part I 41 of the truck until after the locking plunger 84 is moved into locking engagement with the bias piston rod 13, following which, the pressure of fluid in said reservoirs and chamber will continue to reduce to atmospheric pressure. When the pressure of fiuid in the adjusting piston chamber I92 is thus sufficiently reduced, spring I94 will return the adjusting piston 99 to the posi tion in which it is shown on the drawing, but the bias piston 11, and thereby the fulcrum 64, will be maintained in the position to which they are adjusted through the locking action of plunger 84. When the adjusting piston 99 is returned to the position in which it is shown on the drawing, bias spring I43 acting on the rod I36 will move said rod downwardly for moving the surface M9 of the measuring element I39 out of contact with the unsprung part I4I of the truck back to the position in which it is shown in the drawing, and during such movement the bell crank I33, connecting rod I39 and thereby levers I28 and IIS will also be actuated by said spring to return the roller H8 to the position in which it also is shown on the drawing. With the measuring element I39 moved downwardly out of contact with the unsprung part I4I of the truck, the contact therebetween will be avoided during operation of the car in a train around curves, over humps and etc., to prevent damage to these parts.

The venting of fluid under pressure from chamber I45 of the brake cylinder cut-off valve device 35 to a certain pressure, such as 12 pounds, upon movement of the cut-out valve 198 to its cut-out position permits spring I53 to return diaphragm 544 and follower I50 to the position in which they are shown in the drawing. This action perniits spring I58 to seat the exhaust valve I54, thereby closing the connection of pilot chamber 33 to atmosphere, and also permits spring I62 to unseat supply valve I59, thereby connecting brake cylinder pipe II to pilot chamber 33 and thus preparing for normal brake release and application of the equipment.

The venting of fluid under pressure from chamber I65 of compensating cylinder cut-out valve device 31 to a certain pressure, such as 8 pounds, upon movement of the cut-out slide valve I98 to its cut-out position permits spring I1! to return diaphragm I64 and follower I58 to the position in which they are shown on the drawing. This action permits spring I'Ha, to seat exhaust valve I12 thus closing communication between atmospheric chamber I66 and chamber I11 leading by way of passages 38 and 39 to balancing chamber 49, and spring I80 to unseat supply valve 19, thus connecting chamber I15 to chamber 18 leading by way of passage I19 to compensating cylinder pipe 21 and thus preparing for a normal brake release or brake application operation of the equipment.

With the equipment conditioned for operation, and brake pipe 2 fully charged to normal pres sure; if either a service or an emergency reduction in pressure in said brake pipe is effected,

brake controlling valve device I will operate to I supply fluid under pressure from either the auxil iary reservoir 3, or from both the auxiliary reservoir 3 and the emergency reservoir 4, respectively, to the brake cylinder pipe II and thence to the main pressure chamber I8 in the brake cylinder device 6, in the usual well known manner. Fluid under pressure thus supplied to the brake cylinder pipe II will flow through passage I6I and past the open supply valve I58 in the brake cylinder cut-oii valve device 33 to the pilot diaphragm chamber 33 in the load compensating valve device 8. a

Let it be assumed that the fulcrum 64 is in empty position in which it is shown on the drawing. The pressure of fluid in the pilot diaphragm chamber 33 will then deflect the diaphragm 3I downward and rock the beam 4! about the rockable connection with fulcrum 64 and thereby act through stem 44 to move the diaphragm 32 and nut 46 in an upward direction into contact with the release valve 53 and then actuate said valve to open the supply valve 59. Upon opening the supply valve 59 fluid under pressure from the load reservoir 1 will flow through pipe 62, passage fiI and the supply valve chamber 69 to chamber 49 and thence through passage 39 to chamber I15 in the compensating cylinder cutoff valve device 31, then past valve I12 to chamber I19, whence it flows through passage I19 and pipe 21 to the compensating pressure chamber 24 in the brake cylinder device 9. At the same time fluid under pressure will flow from chamber 49 through a choke 33 to chamber 36 at the upper side of diaphragm 32. Choke 38 is merely a stabilizing choke and its purpose is to prevent the pressure in diaphragm chamber 36 from increasing more rapidly than that in the pressure chamber 24 of the brake cylinder device 6.

Fluid under pressure will thus continue to be supplied to the compensating pressure chamber 24 in the brake cylinder device 5 and the diaphragm chamber 36 until such pressure acting on diaphragm 32, which acts on one end of the beam M, is increased to a degree sufficient to overbalance the pilot pressure in chamber 33 acting on diaphragm 3| plus the pressure of spring 239, whereupon diaphragm 32 will be deflected downwardly to permit closing of the supply valve 53 by spring 53 for preventing further flow of fluid under pressure to compensating pressure chamber 24 in the brake cylinder device 6. When the supply valve 59 is closed, as just mentioned, there will be no further flow of fluid under pressure to and consequent increase in pressure of fluid in diaphragm chamber 36 whereupon deflection of diaphragm 32 will cease in a lap position in which the fluid pressure release valve 53 is still seated with the fulcrum 34 in the empty position, substantially midway between the diaphragm stems 49a and. 44. The pressure of fluid obtained in the compensating pressure chamber 24 of the brake cylinder de- Vice 3 will therefore be limited to a degree slightly greater than the pressure of fluid in the main brake cylinder pressure chamber I8 as determined mainly by the pressure of spring 209 on diaphragm 32.

The pressure of fluid thus provided in the compensating pressure chamber 24 of the brake cylinder device 9 acts over the area of the brake cylinder piston I1 outside of the hollow stem El, and the force thus created is less than that due to pressure of fluid in the main pressure chamber I8 acting over the full area of said piston, so that said piston will be forced in the direction of the right hand against the release spring 3fl'to apply the brakes to a degree equal to the differential between these forces, as required to-provide the desired braking of an empty car.

It should be noted that a certain degree of fluid pressure, such as 10 pounds, must be developed in the pilot diaphragm chamber 33 in order to overcome the opposing pressure spring 209 and become effective to actuate the scale beam 4|, thereby preventing or delaying the development of fluid pressure in the compensating chamber of the brake cylinder device 6 until pressure has developed in the pressure chamber l8. The purpose of this is to prevent the possible occurrence of a development of a fluid pressure in compensating cylinder 24 prior to development of fluid pressure in pressure chamber l8 and thereby prevent the possibility of blowing the packing cup off of or away from the piston head 19 of the piston ll.

Now assume that the fulcrum 64 is adjusted V midway between its empty and full load positions, for example, for a car half loaded, fluid will be provided in a compensating pressure chamber 24 in the brake cylinder device 6, and thereby in diaphragm chamber 36 in the compensating device 8, until the pressure thereof minus that of spring 289 is able to over-balance the pressure in the pilot diaphragm chamber 33 so as to permit closing of its supply valve 59, whereby the brakes on the car will be applied by 'a force, equal to the pressure of fluid in chamber [8 acting on the full area of piston H less the opposing pressure of fluid in the compensating pressure chamber 24 acting on a smaller area of said piston, which opposing pressure is proportional to the semi-loaded condition of the car, whereby the braking power delivered by the brake cylinder device 6 for braking the car will be proportional to the semiloaded condition thereof. It will be apparent that for any other adjustment of the fulcrum 64 between its empty and full load positions the pressure of fluid in the compensating pressure chamber 24 of the brake cylinder device 6 will be correspondingly limited so as to provide a braking force for the car proportional to the degree of load on the car.

In case an emergency reduction in pressure in the brake pipe 2 is effected for obtaining an emergency application of the brakes, the pressure in said brake pipe and thereby in the cutoff valve chamber I92 of the cut-off valve device- I46 will be reduced to atmospheric pressure, and when the pressure of fluid in said chamber becomes reduced to a degree below the opposing force of spring I81, said spring will actuate diaphragm I83 and the slide valve I98 back to their cut-in position, in which they are shown on the drawing. The pressure of fluid against which spring I81 can thus return the cut-off slide valve 598 to its cut-in position is however, lower (for instance 8 pounds) than that required in the latch diaphragm chamber 88 for actuating the diaphragm 81 for moving latch 84 out of locking engagement with the bias piston rod 14, so that the position of the fulcrum 64 will not change under such a condition.

In applying the car brakes, as abovedescribed, it will be noted that on a fully loaded car the spring 289 acts to hold the release valve 53 open to permit the pressure of fluid in pressure chamber 24 of the brake cylinder device 6 to remain at atmespheric pressure. When the. car is less than fully loaded however, the spring 209 acts to delay opening of the supply valve 59 by fluid under pressure acting on the pilot diaphragm 3|, and thus acts to correspondingly delay establishment of pressure of fluid in the compensating pressure chamber 24 of the brake cylinder device 6 until after a sufficient pressure of fluid is obtained in the main pressure chamber! to actuate the brake cylinder piston I! to positively and promptly move the brake shoes on the car into frictional engagement with the car wheels, following which, pressure of fluid in said compensating chamber will increase substantially in unison with that in the main pressure chamber l8 for limiting the degree of braking on a car in accordance with the load carried thereby.

Upon an increase in pressure of fluid in brake pipe 2 for causing operation of the brake controlling valve device I to effect a. release of fluid under pressure from the brake cylinder pipe II and thereby from the main pressure chamber l8 in the brake cylinder device 6 for releasing the brakes on a car, a corresponding reduction in pressure of fluid in pilot diaphragm chamber 33 will occur. As the pressure of fluid in chamber 33 is thus reduced the pressure of fluid in chamber 36, plus the pressure of spring 209, will deflect the diaphragm '32 and thereby rock the scale beam 4| about its fulcrum 64 for pulling the nut'extension 48 out of engagement with the release valve 53. Upon opening of the release valve 53 fluid under pressure will be released from the compensating pressure chamber 24 in the brake cylinder device 6 with the release of fluid under pressure from the main pressure chamber Hi. When the pressure of fluid in pressure chamber 18 of thebrake cylinder device 6 is thus reduced sufficiently the brake cylinder release spring 30 will return piston I! to its release position shown in the drawing, whereby the brakes on the car will be released.

It will of course be evident that when the fulcrum 64 is in full load position and no fluid pressure is provided in the brake cylinder compensating pressure chamber 24 in effecting an application of brakes, there will be no release of fluid therefrom in effecting a release of brakes, and therefore there will be no flow of fluid past the open release valve 53 into said chamber as the brake cylinder piston I1 is returned to its release position, it being noted that the open release valve 53 on a fully loaded car provides in effect a breather connection between the brake cylinder compensating pressure chamber 24 and atmosphere. V 7

When the brakes of the car are released, the spring 209 acting on diaphragm 3| insures that the release valve 53 will remain open to dissipate to atmosphere any leakage of fluid that may occur' past the supply valve 59, to thereby insure against such pressure becoming effective in the compensating pressure chamber 24 of the brake cylinder device 6 when not desired and which might interfere with a subsequent application of brakes.

When the car is set out on a siding for' loading, or for unloading and reloading, the brake pipe 2 will be open to atmosphere and the brake cylinder device 6 will be operated to apply the brakes on a car in the same manner as above described and to a degree corresponding to the empty or loaded condition thereof. When the car is again picked up and placed in a train the compensating valve device 8 will again operate in response to charging of the brake pipe 2 to adjust, or readjust if necessary, the position of the fulcrum 64 in accordance with the empty or loaded condition thereof in the same manner as hereinbefore described, whereby during operation of the car in a train the degree of braking of the car will again be limited in accordance with the empty or loaded condition thereof.

Description-Fig. 3

In the structure disclosed in Fig. 1, it will be noted that during charging of the brake pipe 2 and prior to movement of the cut-off valve device I46 to its cut-ofi position in response to increase in pressure in the brake pipe to 40 pounds, the pilot diaphragm chamber 33 was disconnected from the brake cylinder pressure chamber it and vented by operation of the brake cylinder cutof'f valve device 35 while chambers 36 and 49 above the balancing diaphragm 32 were disconnected from the brake cylinder compensating pressure chamber 24 and vented by operation of the compensating cylinder cut-off valve device 31, whereby both ends of the beam H were relieved of force during adjustment of fulcrum {it while the brakes were applied in order to facilitate accurate adjustment of said fulcrum and minimize wear between said fulcrum and beam. The same result of unloading beam ll during adjustment of fulcrum 4] may also be accomplished by the more simple structure shown in Fig. 3 of the drawings.

The structure shown in Fig. 3 difiers from that shown in Fig. 1, for purpose of illustration, only in that it does not embody the compensating cylinder cut-off valve device 3! whereby the balancing chambers 36, 49 are in permanent communication with pipe 21 and thence with the compensating brake cylinder pressure chamber 24. Thus upon charging the brake pipe 2 to effect a release of brakes following the car having been set out on a siding for loading or removal of a load the pilot diaphragm chamber 33 will be vented by operation of the brake cylinder cut-off valve device 35 as above described in connection with Fig. l whereupon the beam 4! will assume its release position to open the release valve 53 and vent the fluid under pressure from the balancing chambers 38, 39 and compensating brake cylinder pressure chamber 24. Both ends of the beam M will thereby be unloaded to permit ready adjustment of the fulcrum 64 in the same manner as in r' the structure shown in Fig. 1. Otherwise operation of the structure shown in Fig. 3 is the same as that shown in Fig. l, the same reference numerals being applied to corresponding parts in both structures to facilitate an understanding.

Summary It will now be seen that I have provided a. valve means for load compensating brake apparatus having a relay valve device of the scale beam type with a shiftable fulcrum, which means operates to relieve the scale beam of the balancing forces during the load adjusting operation whereby a simple knife edge may be employed as a fulcrum.

Having now described the invention, what we claim as new and desire to secure by Letters Patent, is:

1. In a variable load brake equipment, in combination, a brake pipe, brake controlling means operative upon a reduction in pressure of fluid in said brake pipe to effect an application of the brakes on the vehicle, a load compensating mechanism for limiting the degree of said application in accordance with the degree of load carried by said vehicle, said mechanism com- 18 prisin a scale beam for balancing a pilot pressure against another pressure for limiting the degree of said application in accordance with the degree of load carried by said vehicle, a fulcrum rockably supporting said scale beam and shiftable to,

various positions relative thereto, motor means operable in response to a certain degree of pressure of fluid to shift said fulcrum relative to said scale beam according to the load carried by the vehicle, and valve means responsive to a predetermined degree of fluid pressure lower than said certain degree to reduce the pressures balancing on said scale beam to atmosphere.

2. In a variable load brake equipment, in combination, a brake pipe, brake controlling means operative upon a reduction in pressure of fiuid in said brake pipe to effect an application of the brakes on said vehicle, a load compensating mechanism for limiting the degree of said application in accordance with the degree of load carried by said vehicle, said mechanism. comprising a scale beam for balancing a pilot pressure against another pressure for limiting said application, a fulcrum rockably supporting said scale beam and shiftable to various positions relative thereto, motor means operable in response to a certain degree of fluid pressure in said brake pipe to shift said fulcrum relative to said scale beam according to the load carried by the vehicle, and valve means responsive to a predetermined degree of fluid pressure in said brake pipe lower than said certain degree to reduce the pressures balancing on said scale beam to atmosphere.

3. In a variable load brake equipment for a vehicle having a sprung part and an unsprung part, a brake pipe, a brake cylinder device comprising a casing and a piston therein dividing said easing into a main pressure chamber at one side of said piston and a compensating chamber at the opposite side and operative to provide a braking force on said vehicle equal to the difference in effect of fluid pressure in said chambers on said piston, brake controlling means operative upon a reduction in brake pipe pressure to supply fluid under pressure to said main chamber, a compensating device comprising an adjustable fulcrum and a scale beam supported and operative on said fulcrum and subject opposingly to pressures of fluid in said chambers for varying the pressure of fluid in said compensating chamber in accordance with the adjustment of said fulcrum and the degree of pressure of fluid in said main chamber, adjusting means operable in response to a certain degree of fluid pressure to adjust said fulcrum relative to said lever in accordance with the position of said sprung part with respect to said unsprung part, and valve means operable in response to a degree of fluid pressure lower than said certain degree to cut off the connections of said chambers with said compensating device and to reduce the fluid pressure acting on said scale beam to atmosphere.

4. In a variable load brake equipment for a vehicle having a sprung part and an unsprung part, a brake pipe, a brake cylinder device comprising a casing with a piston therein dividin said casing into a main pressure chamber at one side of said piston and a compensating chamber at the opposite side and operative to provide a braking force on said vehicle equal to the difference in effect of fluid pressure in said chambers on said piston, brake controlling means operative upon a reduction in brake pipe pressure to supply fluid under pressure to said main l9 chamber and upon an increase in pressure insaid brake pipe to release fluid under pressure from said main chamber, a compensating device comprising an adjustable fulcrum and a scale beam supported and operative on said fulcrum and subject opposingly to pressures of fluid in said chambers for varying pressure of fluid in said compensating chamber in accordance with the adjustment of said fulcrum and the degree of pressure of fluid in said main chamber, adjusting means operable in response to a certain degree of fluid under pressure to adjust said fulcrum relative to said lever in accordance with the position of said sprun part with respect to said unsprung part, and valve means operable in response to a degree of fluid pressure lower than said certain degree to cut off the connection of a said main chamber with said compensating device and to reduce the fluid pressure previously supplied to said compensating device to atmosphere.

5. In a variable load brake equipment, in combination, a brake pipe, a brake cylinder de vice comprising a casing and a piston therein dividing said casing into a main pressure chamber at one side of said piston and a compensating chamber at the opposite side and operative to provide a braking force on said vehicle equal to the dfference in effect of fluid pressures in said chambers on said piston, a compensating device comprising an adjustable fulcrum and a scale beam supported by and operative on said fulcrum and subject opposingly to pressure, of fluid in a pilot chamber and the pressure of fluid in a balancing chamber for varying the pressure of fluid in said balancing chamber in accordance with the pressure of fluid in said pilot chamber and adjustment of said fulcrum, brake controlling means operative upon a reduction in brake pipe pressure to supply fluid under pressure to said main pressure chamber, adjusting means operative in response to a certain degree of fluid pressure to adjust said fulcrum relative to said scale beam in accordance with the load carried by the vehicle, and, valve means having one sition in which said main chamber is connected to said pilot chamber and said balancing chamber is connected to said compensating chamber and operative in response to a predetermined degree of fluid pressure lower than said certain degree to another position in which the mentioned chamber in the compensating device are out off from the mentioned chambers in said brake cylinder device and connected to atmosphere.

6. In a variable load brake equipment, in combination, a brake pipe, a brake cylinder device comprising a casing and a piston therein dividing said casing into a main pressure chamber atone side of said piston'and a compensating chamber at the opposite side and operative to provide a braking force on said vehicle equal to the difference in effect of fluid pressure in said chambers on said piston, a compensating device comprising an adjustable fulcrum and a scale beam supported by and operative on said fulcrum and subject opposingly to pressure of fluid in a pilot 7 chamber and the pressure of fluid in a balancing chamber for varying the pressure of fluid in said balancing chamber in accordance with the pressure of fluid in'said pilot chambertand the ad justment of said fulcrum, brake controlling means operative upon a reduction in brake pipe pressure to supply fluid under pressure to said main pressure chamber, adjusting means operative in response to a certain degree of fluid pressure to adjust said fulcrum relative to said scale beam in accordance with the load carried by the vehicle, and valve means having one position in which said main chamber is connected to said pilot chamber and operative in response to a predetermined degree of fluid pressure lower than said certain degree to another position in which said pilot chamber is out 01f from the main pressure chamber and the pilot chamber is connected to atmosphere.

7. In a variable load brake equipment for a vehicle having a sprung part and'an unsprung part, a brake pipe, a brake cylinder device comprising a casing and a piston therein dividing said casing'into a main pressure chamber at one side of said piston from a compensating chamber at the opposite side and operative to provide a braking force on said vehicle equal to the difference in eflect of fluid pressure'in said chambers on said piston, brake controlling means operative upon a reduction 'in brake pipe pres sure to supply'fluid under pressure to said main chamber, a compensating device comprising an adjustable fulcrum and a scale beam supported and operative on said fulcrum and subject opposingly, to pressures of fluid in a pilot chamber open to said main pressure chamber and a balancing chamber open to said compensating chamber for varying the pressure of fluid in said compensating chamber in accordance with the adjustment of said fulcrum and the pressure of fluid in said main chamber, adjusting means operable in response to a certain degree of fluid pressure in accordance with the position of said sprung part with respect to said unsprung part to correspondingly adjust'said fulcrum relative to said lever, valve means operable in response to a degree of fluid pressure lower than said certain degree to cut off communication of said balancing chamber with said compensating chamber and to reduce fluidpressure in said balancing chamber to atmosphere, and valve means operative in response to a degree of pressure in a control chamber greater than said predetermined degree and less than said certain degree of pressure to cut off communication of said pilot chamber With said brake cylinder device and to reduce the pressure of fluid in said pilot chamber to atmosphere.

in effect of fluid pressure in said chambers on saidpiston, brake controlling means operative upon a reduction in brake pipe pressure to supply fluid under pressure to said main chamber, a compensating device comprising an adjustable fulcrum and a scale beam supported and operative on said fulcrum and subject opposingly to pressures of fluid in a pilot chamber open to said main pressure chamber and a balancing'chamber open to said compensating chamber for varying the pressures of fluid in said compensating chamber in accordance with the adjustment of said fulcrum and. the pressure of fluid in the said main chamber; adjusting means operable in response to a certain degree of pressure in ac-' cordance with the position of said sprung part with respect to said unsprung part to corre spondingly adjust said fulcrum relative to said chambers beam, and valve means interposed between :said

compensating device and said brake cylinder device for controlling communication between said main pressure chamber and said pilot chamber and between said compensating chamber and said balancing chamber, said valve means being operative in response to a predetermined zone of fluid pressure in one control chamber lower than said certain degree to cut oil said compensating chamber from said balancing chamber and to vent said balancing chamber to atmosphere and operative in response to a zone of pressure in another control chamber greater than said predetermined zone and less than said certain degree of pressure to \cut off said main pressure chamber from said pilot chamber and to vent said pilot chamber to atmosphere.

9. In a variable load brake equipment for a vehicle having a sprung part and an unsprung part, a brake pipe, a brake cylinder device comprising a casing and a piston therein dividing said casing into a main pressure chamber at one side of said piston and a compensating chamber at the opposite side of said piston and operative to provide a braking force on said vehicle equal to the difference in effect of fluid pressure in said chambers on said piston, brake controlling means operative upon a reduction in brake pipe pressure to supply fluid under pressure to said main chamber and upon an increase in pressure in said brake pipe to release fluid under pressure from said main chamber, a compensating valve device comprising an adjustable fulcrum and a scale beam supported and operative on said fulwith the position of said sprung part with re- .spect to said unsprung part to correspondingly adjust said fulcrum relative to said lever, and valve means operable in response to a degree of fluid pressure in a control chamber lower than said certain degree to cut ofi communication between said main pressure chamber and said pilot chamber and to reduce the fluid pressure in said pilot chamber to atmosphere.

10. In a variable load brake equipment, in combination, a brake pipe, a brake cylinder device comprisin a casing and a piston therein dividing said casing into a main pressure chamber at one side of said piston and a compensating chamber at the opposite side and operative to provide a braking force on said vehicle equal to the difference in effect of fluid pressure in said on said piston, brake controlling means operative upon a reduction in brake pipe pressure to supply fluid pressure to said main chamber and upon an increase in pressure of said brake pipe to release fluid under pressure from said main chamber, a load compensating mechanism for varying the pressure of fluid in said compensating chamber in accordance with the adjustment or said fulcrum and the pressure of fluid in said main chamber, said mechanism comprising a scale beam subject opposingly to fluid pressures in a pilot chamber and a balancing chamber connected to said compensating chamber and also a fulcrum for rockably supportin said scale beam and shiftable to various positions relative thereto, motor means operative in response to a certain degree of fluid pressure in said brake pipe to shift said fulcrum relative to said scale beam according to the load carried by the vehicle, and valve means establishing communication between said main chamber and said pilot chamber and operative upon an increase of pressure in said brake pipe to a degree less than said certain degree to cut ofl said pilot chamber from said main chamber and to open said pilot chamber to atmosphere.

11. In a variable load brake equipment, in combination, a brake pipe, a brake cylinder device comprising a casing and a piston therein dividing said casing into a main pressure chamber at one side of said piston and a compensating chamber at the opposite side and operative to provide a braking force on said vehicle equal to the difference in effect of fluid pressure in said chambers acting said piston, brake controlling means operative upon a reduction in brake pipe pressure to supply fluid under pressure to said main chamber and upon an increase in pressure in said brake pipe to release fluid under pressure from said main chamber, a load compensatin mechanism for limiting the degree of said application in accordance with the degree of load carried by said vehicle, said load compensating mechanism comprising an adjustable fulcrum and a scale beam rockably supported on said fulcrum subject opposingly to pressure of fluid supplied from said main chamber to a pilot chamber at one end of said scale beam and pressure of fluid in a balancing chamber at the other end of said scale beam for varying the pressure of fluid supplied to said compensating chamber in accordance with the adjustment of said fulcrum and the pressure of fluid in said pilot chamber and main chamber, adjusting means operable in response to a certain degree of fluid pressure in said brake pipe to shift said .fulcrum relative to said scale beam according to the load carried by the vehicle, and valve means establishing communications between said main chamber and said pilot chamber and between said compensating chamber and said balancing chamber responsive to fluid at a pressure below said certain degree to cut off said communication and to open said pilot chamber and said balancing chamber to atmosphere.

12. In a variable load brake equipment, in combination, a brake pipe, comprising a casing and a piston therein dividing said easing into a main pressure chamber at one side of said piston and a compensating chamber at the other side and operative to provide a braking force on said vehicle equal to the difference in effect of fluid pressure in said chambers on said piston, brake controlling means operative upon a reduction in brake pipe pressure to supply fluid under pressure to said main chamber and upon an increase in pressure in said brake pipe to release fluid under pressure from said main chamber, a load compensating mechanism comprising an adjustable fulcrum and a scale beamiockably supported on said fulcrum and subject opposingly to pressure of fluid supplied from said main chamber to a pilot chamber at one end of said scale beam and pressure of fluid in a balancing chamber at the other end for varying the pressure of fluid in said compensating chamber in accordance with the adjustment of said fulcrum and the pressure of fluid in said pilot chamber and main chamber, adjusting means operable in response to a certain to the load carried by the vehicle, valve means establishing communication between said compensating chamber and said balancing chamber responsive to a predetermined degree of pressure less than said certain degree of pressure to cut off said communication and to connect said balancing chamber to atmosphere, and valve means establishing communication between said main chamber and said pilot chamber responsive to a degree of fluid'pressure below said certain degree of pressure and above said predetermined degree supply fluid under pressure to said first brake cylinder pipe and upon an increase in pressure of fluid in said brake pipe to release fluid underpressure from said first brake cylinder pipe, a relay comprising a lever, an adjustable fulcrum and two movable abutments of equal areas subject respectively and opposingly to pressures of fluid in said first and said second brake cylinder pipes and connected to said lever, valve means controlled by rocking of said lever for varying pressure of fluid in said second brake cylinder pipe according'to variations in pressure in said first brake cylinder pipe, motor means operatble in response to a certain degree of fluid pressure to adjust said fulcrum relative to said lever according to the load carried by the vehicle, latch means for degree of fluid pressure in said brakep'ipe toshift said fulcrum relative to said scale beam according holding said fulcrum in an adjusted position and adapted to be rendered ineflective upon supply of fluid at a predetermined degree of pressure less than said certain degree to a control chamber, and valve means operable upon a supply of fluid at a degree of pressure less than said predetermined degree to cut olf said brake cylinder pipes from said movable abutments and to connect said movable abutments to atmosphere. 7 r

14. In a fluid pressure brake equipment, in combination, a brake pipe, first and second brake cylinder pipes, brake controlling means operable upon a reduction in pressure in said brake pipe to supply fluid under pressure to said first brake cylinder pipe and upon an increase of pressure of fluid in said brake pipe to release fluid under pressure from said first brake cylinder pipe, a relay comprising a lever, an adjustable fulcrum and two movable abutments of equal. area subject, respectively, and opposingly to pressure of fluid in said first and second brake cylinder pipes and connected to said, lever, valve means controlled by rocking of said lever for varying pressure of fluid in said second brake cylinder pipe according to variations in pressure in said first brake cylinder pipe, motor means operable in response to a certain degree'of fluid pressure to adjust said fulcrum relative to said. lever according to the load carried by the vehicle, latch means for holding said fulcrum in an adjusted position and adaptable to be rendered ineffective upon a supply of fluid at a predetermined degree of pressure less than said certain degree to a control chamber, valve means operable upon a supply of fluid to a control chamber at a selected degree of pressure: less than said predetermined degree to cut off the second brake cylindergpipe from its respective-movable abutment and to'c'onnect said respective movable abutment to atmosphere,- and valve means operable upon asupply of fluid at to cut ofii said first brake cylinder pipe to the otherabutment and to connect said other abutmerit to atmosphere.

15. In a fluid pressure brake equipment, in combination, a brake pipe, first and second brake cylinder pipes, brake controlling means operable upon a reduction in pressure in said brake pipe to supply fluid. under pressure to said first brake cylinder pipe and upon an increase of pressure of fluid in said brake pipe to release fluid under pressure from said first brake cylinder pipe,'a relay comprising a lever, an adjustable'fulcrum and two movable abutments of equal areas subject, respectively, and opposingly to pressure of fluid in 'said first and second brake cylinder pipes and connected to said lever, valve means controlled by rocking of said lever for varying ful rum, motor means operable in response to a certain degree of fluid pressure to adjust said fulcrum relative to said lever according to the load carried by the vehicle, latch means for holding said fulcrum in an adjusted position and adapted to be rendered inefiective upon supply of fluid at a predetermined degree of pressure loss than said certain degree to a control chamher, and valve means operable upon a supply of fluid at a degree of pressure less than said predetermined degree to cutoff said first brake cylinder pipe from its respective movable abutment and to connect said respective movable abutment to atmosphere.

16. In a fluid pressure brake equipment, in combination, a brake pipe, first and second brake cylinder pipes, brake controlling means operable upon a reduction in' pressure in said brake pipe to sup-ply fluid under pressure to said first brake cylinder pipe and upon an increase in pressure of fluid in said brake pipe to release fluid under pressure from said first brake cylinder pipe, a relay comprising a'lever, an adjustable fulcrum and two movable abutments of equal areas subject respectively and opposingly to pressure of fluid in first and second brake cylinder pipes and connected to said lever, valve means controlled by rocking of said lever for varying the pressure 'of fluid in said brake cylinder pipe according to variations in pressure in said first brake cylinder adapted to be rendered ineffective upon supply. of fluid at a predetermined degree of pressure less than said certain degree to a control chamher, and valve means responsive to a supply of fluid and a degree of pressure less than said predetermined degree to reduce the pressures acting on said movable abutments to atmosphere.

1 7. In a variable load brake equipment, in combination, a brake pipe, brake controlling means operative upon a reduction in pressure 7 of fluid in said brake pipe to effect an applicaof load carried by said vehicle, said mechanism comprising a scale beam for balancing a pilot pressure against a pressure for limiting said application, a fulcrum for rockably supporting said scale beam and shiftable to various positions relative thereto, motor means operable in response to a certain degree of pressure of fluid to shift said fulcrum relative to said scale beam according to the load carried by the vehicle, valve means responsive to a predetermined degree of fluid pressure supplied to a control chamber lower than said certain degree to reduce the pressures balancing on said scale beam to atmosphere, and a cut-off valve device having a cut-in position in which fluid under pressure is supplied from said brake pipe to said valve means and said motor means and operative upon an increase in brake pipe pressure to a degree higher than said predetermined degree to a cut-off position in which the supply of fluid under pressure from said brake pipe is cut off and the control chambers in said valve means and said motor means are open to atmosphere.

18. In a variable load brake equipment, in combination, a brake pipe, brake controlling means operable upon a reduction in pressure of fluid in said brake pipe to effect an application of the brakes on said vehicle, a load compensating mechanism for limiting the degree of said application in accordance with the degree of load carried by said vehicle, said mechanism comprisin a scale beam for balancing a pilot pressure against a pressure for limiting said application, a fulcrum for rockably supporting said scale beam and shiftable to various positions relative thereto, motor means operable in response to a certain degree of pressure of fluid in said brake pipe supplied to a control chamber to shift said fulcrum relative to said scale beam according to the load carried by the vehicle, valve means responsive to a predetermined degree of fluid pressure in said brake pipe supplied to a control chamber lower than said certain degree to reduce the pressures balancing on said scale beam to atmosphere, and a cut-off valve device having a cut-in position in which fluid under pressure is supplied from said brake pipe to said valve means and to said motor means and operative upon an increase in brake pipe pressure to a degree higher than said predetermined degree to a cut-off position in which the supply of fluid under pressure from said brake pipe to said valve means and to said motor means is cut off and the control chambers in said valve means and said motor means are open to atmosphere.

19. In a fluid pressure brake equipment, in combination, a brake pipe, first and second brake cylinder pipes, brake controlling means operable upon a reduction in pressure in said brake pipe to supply fluid under pressure to said first brake cylinder pipe and upon an increase in pressure of fluid in said brake pipe to release fluid under pressure from said first brake cylinder pipe, a relay valve device comprising a lever, an adjustable fulcrum and two movable abutments of equal areas subject, respectively, and opposingly to pressures of fluid in first and second brake cylinder pipes connected to said lever, valve means controlled by rocking of said lever for varying pressure of fluid in said second brake cylinder pipe according to variations in pressure in said first brake cylinder pipe and the position of said fulcrum relative to said lever, motor means operable in response to a certain degree of fluid pressure to adjust said fulcrum relative to said lever according to the load carried by the vehicle, latch means for holding said fulcrum in an adjusted position and adapted to be rendered ineiiective upon supply of fluid at a predetermined degree of pressure less than said certain degree to a control chamber, valve means operable upon a supply of fluid at a selected degree of pressure less than said predetermined degree to a control chamber to cut off said second brake cylinder pipe from its respective movable abutment and connect said respective movable abutment to atmosphere, valve means operable upon a supply of fluid at a degree of pressure less than said selected degree to cut off said first brake cylinder pipe from the other abutment and connect said other abutment to atmosphere, cut-off valve device having a cut-in position in which fluid under pressure is supplied from said brake pipe to said valve means and said motor means and operative upon an increase in brake pipe pressure to a degree higher than said predetermined degree to a cut-off position in which the supply of fluid under pressure from said brake pipe is cut off from the control chambers in said valve means, and said latch means and said motor means are open to atmosphere.

20. In combination, a scale beam, a fulcrum for said beam adjustable relative to the length of said beam, operated means subject to pressure of fluid acting on said beam at one side of said fulcrum, fluid pressure operating means acting on said beam at the opposite side of said fulcrum, means for adjusting said fulcrum, control means for effecting operation of said fulcrum adjusting means, cut-off means having a normal position for rendering said operated and operating means subject to pressure of fluid and having a cut-off position for venting such fluid pressure, locking means for said fulcrum, and means responsive to fluid at less than a chosen degree to effect operation of said cut-off means to its cut-off position, to render said locking means inefiective and to effect operation of said control means, and responsive to fluid at a higher pressure to effect operation of said cut-oif means to its normal position and to render said looking means effective.

EARLE S. COOK. GLENN T. MoCLURE. JOHN W. BUSH.

REFERENCES CITED The following references are of record in the Name Date Cook Mar. 25, 1947 Number 

